Surgical procedures such as laparoscopic procedures require the surgeon to create one or more punctures in the anatomy of the patient to enable a guide tube, referred to as a cannula, to be sited and thereby enable surgical instruments to be passed down through the cannula into the patient in order to carry out the intended procedures.
One method of accomplishing this is the open or "Hussan" method wherein an incision is made in the desired area to accommodate the cannula and sutures are put around the cannula to close the gap left by the incision. Sutures are also made from the skin to cannula to assist in holding the cannula in place. This technique is used primarily (but not exclusively) in situations wherein other abdominal surgeries pose potential adhesion complications. Such complications can cause an unintended puncture in the bowel or in other organs.
A second method involves the use of a mechanical trocar device which comprises the combination of a trocar and a cannula. The trocar basically comprises a rod or shaft having a very sharp cutting edge or point at one end thereof and is enclosed within the tubular cannula. In some devices, the cannula incorporates some kind of safety mechanism, such as a shield, over the cutting tip prior to use to reduce the chance of unintended punctures. Trocar devices characteristically require substantial force to drive the cutting end or tip through, e.g., the abdomen wall and as a result, trocar devices can be hard to control. A separate trocar device, i.e., comprising a trocar and cannula, is used for each puncture site.